Playback apparatus

ABSTRACT

A playback apparatus for playing back picture information from a storage medium storing still picture group management information (VOBGI) for managing still picture data (VOB) and N still picture data (VOB) as a still picture group (VOBG), where N being an integer number equal to or larger than one. The still picture group management information (VOBGI) includes a first recording time (F_RECTM) at which the still picture data (VOB) in the still picture group (VOBG) was recorded first and a last recording time (L_RECTM) at which the still picture data (VOB) in the still picture group (VOBG) was recorded last. The playback apparatus includes a user interface for inputting a predetermined time (TM), a control unit for comparing the predetermined time with the first and last recording times (F_RECTM, L_RECTM), and an arrangement for reading out the still picture data (VOB) and playing back the still picture.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a rewritable storage medium, arecording apparatus and a playback apparatus for use with the storagemedium, a method for recording data on the storage medium, and to acomputer program executing the recording method. More particularly, thepresent invention is adaptive to, and preferably used with, an opticaldisc on which a large amount of still picture data is recorded.

[0002] Large-capacity, rewritable optical disc recording media, such asDVD-RAMs or DVD-RWs, have been made available, and many technologies forrecording picture data or audio data on the media are now beingdeveloped. Video data coded, for example, in the MPEG (Moving PictureExperts Group) system described in the ISO/IEC11172 or ISO/IEC13818standard is usually used. Still picture data coded in the intraframecompression method (I picture) of the MPEG (Moving Picture ExpertsGroup) system or in the JPEG system described in the ISO/IEC10918-1standard is usually used.

[0003] Digital VCRs (digital video cassette recorders) using magnetictapes as recording media or electric still cameras using memories suchas a flash memory as recording media are already in practical use forstoring coded video or still pictures with audio.

[0004] Recording apparatuses using optical discs as recording media,such as DVD-RAMs, have many advantages over conventional digital VCRs orelectric still cameras in that they feature random accessibility whichcannot be attained by magnetic tapes, large-capacity which cannot beachieved by memories such as a flash memory, and a low cost per bit.Therefore, recording apparatuses using optical disc media allow the userto play back data independently of the sequence in which data wasrecorded and to process as many as tens of thousands of still pictures.For this reason, optical disc recording media are expected to be widelyused as new AV (audio-visual) recording media.

SUMMARY OF THE INVENTION

[0005] A DVD-RAM disc allows moving pictures and still pictures to bemixed. Especially, for still pictures, a huge number of still pictureswhich cannot be recorded by a conventional electric still camera can berecorded. For example, a 4.7 GB DVD-RAM disc can record thereon about64,000 still pictures each of which is an MPEG-coded still picture (Ipicture) of about 80 KB.

[0006] Unlike a storage medium such as a digital VCR tape from whichdata is played back in the order in which it was recorded, an opticaldisc medium such as a DVD-RAM disc allows the user to access datarandomly. For data to be accessed randomly, management information, suchas the addresses and sizes of still picture data as well as the playbacktimes of audio data recorded with still pictures are recorded.

[0007] Playing back still pictures with a playback apparatus requirestwo steps. First, a still picture data address and so on are read fromthe management data recorded on the optical disk medium, and then stillpicture data recorded at the address that was read is played back.Therefore, when playing back a plurality of still pictures, each stillpicture requires the above two steps.

[0008] Also, recording still pictures and so forth onto an optical discwith a recording apparatus requires two steps. First, still picture datais recorded, and then management information such as the still picturedata address is recorded. Therefore, when recording a plurality of stillpictures, each still picture requires the above two steps.

[0009] The optical disc recording or playback apparatus has an opticalhead for recording and playing back information. This optical head isslow in accessing data because it is larger and heavier than a magnetichead. Therefore, playing back or recording a plurality of stillpictures, which requires two steps, takes long and the apparatus cannotperform random access quickly.

[0010] To solve this problem, the optical disc recording apparatus andthe playback apparatus store management information, read from theoptical disc, into memory. Once the management information is storedinto memory of the playback apparatus, the apparatus need not readmanagement information from the disc each time it plays back a stillpicture, thus reducing the time needed to playback a plurality of stillpictures. Also, the recording apparatus stores management informationabout a plurality of still pictures into the memory of the apparatus andrecords the management information onto the disc at a time. Thiseliminates the need to record management information each time a stillpicture is recorded, thus reducing the time needed to record a pluralityof still pictures.

[0011] However, because a large-capacity storage medium such as aDVD-RAM records tens of thousands of still pictures thereon, the amountof management information on recorded still pictures becomes very largeand a large amount of memory capacity is needed in the apparatus.Although the memory price has gone down recently, it is difficult toinstall megabytes of memory onto an AV apparatus. In addition,considering the memory backup provided for use at emergency, it isunrealistic for an AV apparatus to process megabytes of managementinformation.

[0012] To solve this problem, a technology is disclosed in thespecification of the European Patent Application No. 99304691.1 filed onJun. 16, 1999 or the corresponding U.S. patent application Ser. No.09/332,882 filed on Jun. 15, 1999 by some of the inventors of thepresent invention. To prevent an increase in the management informationsize, the technology disclosed in the above patent application recordsmanagement information, such as data addresses and sizes or audio dataplayback times, in variable-size management information tablesproportional in size to the number of still pictures or the number ofaudio data pieces.

[0013] However, the technology described above does not take thefollowing into account. First, the technology does not support thefunction to manage still picture data recording times. Because thetechnology described above does not support a search for data with theuse of recording times, there is a problem with processing a request tosearch a huge number of still pictures for a desired still picture.

[0014] For example, as shown in FIG. 3, when a recording time (RECTM) isrepresented by a 7-byte data structure composed of the year (2 bytes),month (1 byte), day (1 byte), hour (1 byte), minute (1 byte), and second(1 byte), adding the recording time (RECTM) to each of about 64,000still pictures requires that the data size of the management informationused by the above-described technology be increased by as many as about438K bytes (=64,000×7).

[0015] As mentioned above, the system controller within the apparatusshould have the management information always in its own memory forquick random access. To reduce the memory size (cost reduction) of AVapparatuses, that is, to reduce the cost, the data size of themanagement information must be minimized.

[0016] It is a first object of the present invention to provide arecording apparatus and a playback apparatus, primarily used for opticaldiscs, which allow the user to search for data based on recording timesand which have a data structure preventing the data size of managementinformation from increasing, and computer programs which control theseapparatuses.

[0017] Second, the technology does not support the function to solveproblems associated with still picture deletion.

[0018]FIG. 12 shows the still picture management method according to thetechnology described above. First, still picture group managementinformation (VOBGI) 103 is provided to manage a plurality of stillpicture data pieces (VOB) 101 as a still picture group (VOBG) 102. Thestill picture group management information (VOBGI) 103 comprises stillpicture group identification information (VOBG_ID) 104, start and endaddress information (VOBG_Address) 105 on the still picture group (VOBG)102, number-of-pictures information (V_I_Number) 1015 representing thenumber of still pictures managed in this group, picture managementinformation table (V_I_Table) 1016 containing only picture managementinformation (V_I) 1017 on the pictures of the still picture data (VOB)101, number-of-audio-data information (A_I_Number) 1018 representing thenumber of audio data pieces managed in this group, and audio managementinformation table (A_I_Table) 1019 containing only audio managementinformation (A_I) 1020 on the audio data. The picture managementinformation (V_I) 1017 comprises an picture data size (V_Size) 1021 andaudio pointer information (A_I_PTR) 1022 providing a link to the audiomanagement information (A_I) 1020 corresponding to the audio data to beplayed back in synchronization with the picture. The audio managementinformation (A_I) 1020 comprises audio data address information(A_Address) 1023, audio data size (A_Size) 1024, audio playback time(A_PTM) 1025, and audio pointer information (A_I_PTR) 1026 providing alink to other management information (A_I) 1020. When there is no audiodata to be linked, NULL is recorded in the audio pointer information(A_I_PTR) 1022, 1026 to indicate an invalid value.

[0019] The technology described above has two separate tables: picturemanagement information table (V_I_Table) 1016 and audio managementinformation table (A_I_Table) 1019. In addition, the audio managementinformation (A_I) 1020 contains audio data address information(A_Address) 1023.

[0020] Still picture data and audio data are recorded in files on thestorage medium. Because the addresses in the file are contiguous,deleting a still picture and the audio data synchronizing with it causesthe file to be restructured to close up the deleted part and to make theaddresses contiguous within the file. Therefore, when the recordingposition of audio data is managed by the audio data address information(A_Address) 1023 within the file, all the audio data address information(A_Address) 1023 after the deleted part must be replaced with newaddress information generated after restructuring. This will require avery long time for replacing address information when tens of thousandsof still picture data are recorded.

[0021] Another way to get address information is to simply delete theaddress information 1023 from the management information shown in FIG.12 and then to add up the picture and audio data sizes 1021, 1024beginning with the start, as shown in FIG. 13, (a).

[0022] Although this method eliminates the need for address replacementafter restructuring described above, following problem arises.

[0023] For example, assume that two different data structures describedbelow occur in the file. One data structure, shown in FIG. 13, (b), iscomposed of the video part (V_Part #1) 1027 of still picture #1,followed by the post-recorded audio part (A_Part #1) 1028 of stillpicture #1, followed by the video part (V_Part #2) 1029 of still picture#2. Another data structure, shown in FIG. 13, (c), is composed of thevideo part (V_Part #1) 1030 of still picture #1, followed by the videopart (V_Part #2) 1031 of still picture #2, followed by the post-recordedaudio part (A_Part #1) 1032 of still picture #1. Although the datastructures differ, management information table entries are created asshown in FIG. 13, (a). That is, V_I #1(1017-1) in the picture managementinformation table (V_I_Table) 1016 comprises the picture data size(V_Size #1) 1021-1 of V_Part #1(1027) or V_Part #1(1030) and the audiopointer information (A_I_PTR) 1022-1 providing a pointer to A_Part#1(1028) or A_Part #1(1032). V_I #2(1017-2) comprises the picture datasize (V_Size #2) 1021-2 of V_Part #2(1029) or V_Part #2(1031) and audiopointer information (NULL) 1022-2 indicating that there is no audio datato be linked. A_I #1(1020) comprises the audio data size (A_Size #1)1024 of A_Part #1(1028) or A_Part #1(1032), audio playback time (A_PTM#1) 1025, and audio pointer information (NULL) 1026 indicating thatthere is no audio data to be linked. Therefore, these two cannot bedistinguished.

[0024] In addition, the configurations of the picture managementinformation (V_I)(1017) and the audio management information (A_I)(1020)shown in FIG. 12 are redundant. The data sizes may further be reduced.

[0025] It is a second object of the present invention to provide arecording apparatus and a playback apparatus for use with an opticaldisc with a data management structure capable of managing still picturedata and audio data to be played back in synchronization the stillpicture data without any problem, significantly reducing the time neededto re-configure the management information when still pictures aredeleted, and reducing the management information sizes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]FIG. 1 is a diagram showing the configuration of a firstembodiment of the present invention.

[0027]FIG. 2 is a diagram showing the structure a directory used in thefirst embodiment of the present invention.

[0028]FIG. 3 is a diagram showing the structure of time information usedin the first embodiment of the present invention.

[0029]FIG. 4 is a diagram showing the configuration of a secondembodiment of the present invention.

[0030]FIG. 5 is a diagram showing the structure a directory used in athird embodiment of the present invention.

[0031]FIG. 6 is a diagram showing the configuration of the thirdembodiment of the present invention.

[0032]FIG. 7 is a diagram showing the configuration of a fourthembodiment of the present invention.

[0033]FIG. 8 is a diagram showing the configuration of arecording/playback apparatus of the present invention.

[0034]FIG. 9 is a diagram showing an example of the still picturerecording method according to the present invention.

[0035]FIG. 10 is a diagram showing an example of the still pictureplayback method according to the present invention.

[0036]FIG. 11 is a diagram showing the configuration of an embodiment ofthe present invention.

[0037]FIG. 12 is a diagram illustrating a technology proposed by theinventor and his group.

[0038]FIG. 13 is a diagram illustrating the technology proposed by theinventor and his group.

[0039]FIG. 14 is a diagram showing the detailed configuration of theembodiment of the present invention.

[0040]FIG. 15 is a diagram showing an example of a file used in theembodiment of the present invention.

[0041]FIG. 16 is a diagram showing the configuration of the embodimentof a recording/playback apparatus according to the present invention.

[0042]FIG. 17 is a diagram showing an example of recording method usedin the present invention.

[0043]FIG. 18 is a diagram showing another example of recording methodused in the present invention.

[0044]FIG. 19 is a diagram showing an example of playback method used inthe present invention.

[0045]FIG. 20 is a diagram showing the configuration of the embodimentof the recording/playback apparatus used in the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] An embodiment of the present invention which achieves the firstobject will be detailed.

[0047]FIG. 1 shows the configuration of a first embodiment of thepresent invention. In the figure, N (an integer equal to or largerthan 1) still pictures (VOB) 1 coded, for example, in the I picturecompression method of MPEG are grouped into one still picture group(VOBG) 2. Group generation is controlled so that the next still picturegroup (VOBG) 2 is generated when the number of still pictures (VOB) 1 ofthe still picture group (VOBG) 2 reaches a predetermined value (forexample, 64) during still picture recording or when the operation modeis switched from video recording mode to still picture recording mode.Data (coded stream data) of the still pictures (VOB) 1 is recorded on astorage medium as a VOB file 11 which will be described later, whileinformation used to define the still picture groups (VOBG) 2 is recordedon the storage medium as a VOB management file 12.

[0048] The VOB management file (VOBGI) 12 comprises managementinformation (VOBGI) 3 corresponding to each still picture group (VOBG)2. That is, each still picture group (VOBG) 2 has its own managementinformation (VOBGI) 3 in this file. Note that information used to manageM (an integer equal to or larger than 1) pieces of managementinformation (VOBGI) 3 may be provided separately in the VOB managementfile (VOBGI) 12. This information is not shown in the figure. Themanagement information (VOBGI) 3 comprises a still picture groupidentifier (VOBG_ID) 4, number-of-VOBs information 5, a VOB map 6, afirst recording time (F_RECTM) 7, and a last recording time (L_RECTM) 8.Each entry will be described below.

[0049] The still picture group identifier (VOBG_ID) 4, a unique value inthe VOB management file 12, identifies each piece of managementinformation (VOBGI) 3 and the corresponding still picture group (VOBG)2. Serial numbers beginning with the start of the VOB management file 12may be used for this information, in which case the still picture groupidentifier (VOBG_ID) 4 may be omitted.

[0050] The number-of-VOBs information 5 indicates the number of stillpictures (VOB) 1 of the still picture group (VOBG) 2. Thisnumber-of-VOBs information determines the data length of the VOB map 6which will be described below.

[0051] The VOB map 6 contains information on the address 9 and theattribute (10) of each still picture (VOB) 1. Note that it is alsopossible to store data sizes, instead of addresses 9, and to find theaddress of a desired location by add up (summation) the data sizesbeginning at the start and ending at the address immediately precedingthe location. The attribute (10) includes the number of horizontal andvertical pixels of the still picture, still picture display time,whether or not there is audio to be played back in synchronization withthe still picture, audio play back time, and audio data address.

[0052] Although the recording time (RECTM) of each still picture (VOB) 1may be stored as management information as described above, this methodmakes the data size of management information too large. The firstrecording time (F_RECTM) 7 and the last recording time (L_RECTM) 8 areone of characteristics of the present invention. Therefore, to reducethe data size, the recording times (RECTM) are stored for each stillpicture group (VOBG) 2 which groups N (an integer equal to or largerthan 1) still pictures (VOB) 1. In addition, storing both the firstrecording time (F_RECTM) 7 and the last recording time (L_RECTM) 8 ofthe still picture recording times (RECTM) of the still picture group(VOBG) 2 makes it possible to make a search with a time as the key. Thatis, when the user enters the recording time (TM) of a still picture tobe played back or searched for, only the still picture group (VOBG) 2corresponding to the recording time (TM) is selected for playback orsearch. That is, only the still picture group (VOBG) 2 whose TM is equalto or later than F_RECTM and equal to or earlier than L_RECTM(F_RECTM(7)≦TM≦L_RECTM(8)) is selected. According to the presentinvention, the data management structure shown in FIG. 1, when recordedon the optical disc, eliminates for the user to search the maximum ofabout 64,000 still pictures for one desired still picture. Instead, itallows the user to search the maximum number of still pictures (forexample, 64) of a still picture group (VOBG) for the desired stillpicture. Therefore, usability is significantly increased.

[0053]FIG. 2 shows an example of directory structure used in the firstembodiment of the present invention. On recording media such as aDVD-RAM, coded stream data such as still pictures, managementinformation, and so on are recorded as files containinglogically-related data. A storage medium, with a directory structurebeginning at a root directory 13, usually has the above-described VOBfile 11 and VOB management file 12 generated and stored in asub-directory 14. Note that, instead of using the subdirectory 14, theVOB file 11 and the VOB management file 12 may be recorded directlybelow the root directory 13. The file 11 and the VOB management file 12may also be stored in another sub-directory which is below thesubdirectory 14.

[0054]FIG. 3 shows the structure of time information used in the firstembodiment of the present invention. The figure shows an example of thedata structure of a recording time (RECTM) represented by a 2-byte foryear 15, 1-byte for month 16, 1-byte for day 17, 1-byte for hour 18,1-byte for minute 19, and 1-byte for second 20. This data structure maybe used also for the first recording time (F_RECTM) 7 and last recordingtime (L_RECTM) 8 described above. This data structure, if used for thestill picture group (VOBG), requires only 14 additional bytes forF_RECTM and L_RECTM. Thus, even if the maximum of about 64,000 stillpictures are recorded, with each 64 pictures grouped as a still picturegroup, this data structure requires about only 14K bytes(=(64,000×14)/(64×1,024)) of additional space for the managementinformation. As compared to the above-described technology in which arecording time is appended to each still picture and therefore themanagement information is increased by as many as about 438K bytes, theembodiment of the present invention increases the management informationonly by about 3%.

[0055] This reduces the amount of management information and the amountof memory that must be installed in the recording/playback apparatus,thus increasing the access speed while reducing the cost.

[0056] It should be noted that the present invention is not limited tothe data structure shown in the figure but that the recording time maybe represented by a data structure represented by the numbers of bytesother than those shown above. In addition, the recording time may berepresented by the total number of seconds beginning at a predeterminedtime (for example, 00:00:00 on Jan. 1^(st), 1990).

[0057]FIG. 4 shows the configuration of a second embodiment of thepresent invention which achieves the first object of the presentinvention. The figure shows the management information structure whichcontains the recording time (RECTM) of each still picture data (VOB) onthe optical disc medium but which reduces the amount of memory thesystem controller of the apparatus must hold. Like the structure shownin FIG. 1, the management information (VOBGI) 3 comprises still picturegroup identifier (VOBG_ID) 4, number-of-VOBs information 5, VOB map 6,first recording time (F_RECTM) 7, and last recording time (L_RECTM) 8.The management information (VOBGI) 3 further comprises pointerinformation (RECTMI_P) 21 pointing to still picture recording timemanagement information (RECTMI) 22. This pointer information (RECTMI_P)21 points to the address within the VOB management file 12 where thestill picture recording time management information (RECTMI) 22 isstored and may further contain the data size of the still picturerecording time management information (RECTMI) 22. Also, with the stillpicture recording time management information (RECTMI) 22 as a fileseparate from the VOB management file 12, the file name may be stored asthe pointer information (RECTMI_P) 21.

[0058] The still picture recording time management information (RECTMI)22 contains the recording times (RECTM) 23 of the still pictures (VOB) 1of each still picture group (VOBG) 2. In the example shown in thefigure, five still pictures (VOB) are grouped as a still picture group(VOBG). The recording time (RECTM) may be represented by the datastructure shown in FIG. 3.

[0059] In this configuration, the system controller holds only themanagement information (VOBGI) 3 in its own memory. When the recordingtime of each still picture data (VOB) is required, only the stillpicture recording time management information (RECTMI) of the stillpicture group (VOBG) to which that still picture (VOB) belongs is readinto memory. Therefore, this configuration may reduce the size ofrequired memory. For example, if the pointer information (RECTMI_P) is 4bytes, the maximum number of still pictures of a still picture group(VOBG) is 64, the maximum number of still picture groups is 1,000(=64,000/64), and the recording time (RECTM) is 7 bytes, then theincrease in required memory is 4,448 bytes (=4×1,000+64×7). Thus, thetotal of this increase and the increase required for F_RECTM 7 andL_RECTM 8 is about 4% of the increase (about 438K bytes) according tothe technology described above.

[0060]FIG. 5 shows the configuration of a directory used in a thirdembodiment of the present invention to achieve the first object. Therecording times (RECTM) of still pictures (VOB) 1 are used primarily forsearch. Recording times are usually displayed with thumbnail pictures,which are reduced still pictures, for use in search. Thus, a THM file 24storing therein thumbnail pictures to be searched for and a THMmanagement file 25 storing therein thumbnail picture managementinformation, which will be described later, are added to the directorystructure shown in FIG. 2. This allows the recording times (RECTM) ofstill pictures (VOB) 1 to be managed in the THM management file 25.Although the THM file 24 and the THM management file 25 are in thedirectory in which the VOB file 11 and the VOB management file 12 arestored, they need not be in that directory but may be in some othersubdirectory.

[0061]FIG. 6 shows the configuration of a third embodiment of thepresent invention. The figure shows how the recording times (RECTM) 32of the still pictures (VOB) 1 are stored in the THM management file 25.Like still picture management information (VOBI) 26 for managing stillpictures (VOB) 1, thumbnail management information (THMI) 29 formanaging thumbnail pictures 28 need not reside in memory. It need onlybe read into memory at search time. Therefore, with the recording times(RECTM) 32 recorded in the thumbnail management information (THMI) 29,there is no need to increase the amount of memory the system controllermust hold. At the same time, because there is a one-to-onecorrespondence among still pictures (VOB) 1, thumbnail pictures 28, andthumbnail management information (THMI) 29 as shown in the figure, therecording times (RECTM) 32 of the still pictures (VOB) 1 may be stored.In the figure, thumbnail identifiers 27, 30, each unique value in theVOB management file 12 and in the THM management file 25 respectively,are identification information for associating the VOB managementinformation (VOBI) 26 with the thumbnail management information (THMI)29.

[0062] Serial numbers beginning with the start of the VOB managementfile 12 may also be used for thumbnail identifiers 27, in which casethumbnail identifiers 30 may be omitted. In addition, addressinformation 31 on a position within the THM file, stored in thethumbnail management information (THMI) 29, allows the thumbnailmanagement information (THMI) 29 to be made to correspond to thumbnailpictures 28. In the method shown in the figure, each still picture (VOB)1 must have its own still picture management information (VOBI) 26 andtherefore the size of the VOB management file 12 residing in memoryincreases. This method may be improved as described below.

[0063]FIG. 7 shows the configuration of a fourth embodiment of thepresent invention to achieve the first object. Like the method shown inFIG. 1, N (N is an integer equal to or larger than 1.) still pictures(VOB) 1 are grouped into a still picture group (VOBG) 2, and the stillpicture group management information (VOBGI) 3 corresponding to eachstill picture group (VOBG) 2 manages the group. In addition to theentries in the data structure shown in FIG. 1, the still picture groupmanagement information (VOBGI) 3 has pointer information (THMGI_P) 33pointing to thumbnail group management information (THMGI) 34 which willbe described later. This pointer information (THMGI_P) 33 points to theaddress within the THM management file 25 at which thumbnail groupmanagement information (THMGI) 34 is stored. This information may alsocontain information on the data size of the thumbnail group managementinformation (THMGI) 34 and the address name of the THM management file25.

[0064] The thumbnail group management information (THMGI) 34 isinformation for managing thumbnail groups (THMG) 40 each composed of L(L is an integer equal to or larger than 1.) thumbnail pictures 28. Withthe value of L made equal to the value of N indicating the number ofstill pictures (VOB) 1 of a still picture group (VOBG) 2, both groupssynchronize with each other and therefore management becomes easy. Allthumbnail group management information (THMGI) 34 is collected andrecorded as the THM management file 25.

[0065] The thumbnail group management information (THMGI) 34 comprisesnumber-of-thumbnails information 35 and a THM map 36. Thenumber-of-thumbnails information 35 indicates the above-mentionedinteger L. When L is equal to N as described above, the number-of-VOBsinformation 5 in the still picture group management information (VOBGI)3 may be used for L and therefore L may be omitted. The THM map 36contains the address 37, attribute 38, and recording time (RECTM) 39 ofeach thumbnail picture 28. Note that, if the data size of a thumbnailpicture (THM) is stored instead of the address (37), adding up the datasizes beginning at the start gives us the address of a desired entry.The attribute 38 includes such information as the number of vertical andhorizontal pixels and coding method; if they are fixed, the attributemay be omitted.

[0066] The method described above, when used for making a search basedon times, first finds the desired still picture group (VOBG) with theuse of the first recording time (F_RECTM) 7 and the last recording time(L_RECTM) 8 of each group recorded in the still picture group managementinformation (VOBGI) 3. Then, the method reads into memory only thethumbnail group management information (THMGI) 34 corresponding to thestill picture group (VOBG). This prevents the memory size of the systemcontroller from increasing. For example, if the pointer information(THMGI_P) 33 is 4 bytes and the maximum number of still picture groups(VOBG) is 1,000 (=64,000/64), then the VOB management file becomes 4,000bytes larger than that used in the method shown in FIG. 1. If themaximum number of thumbnail pictures 28 of a thumbnail group (THMG) 40is 64, the number-of-thumbnails information 35 is omitted by setting Lequal to N, the address 37 is 4 bytes, the attribute 38 is omitted, andif the recording time (RECTM) 39 is 7 bytes, then the size of thethumbnail group management information (THMGI) 34 is 704 bytes(=64×(4+7)) for each group. Thus, as compared to the method shown inFIG. 1, the addition of only 4,704 bytes allows the recording time(RECTM) 39 of each still picture (VOB) 1 to be searched for. The totalof this increase and the increase required for F_RECTM 7 and L_RECTM 8(about 14K bytes) described above is about 4.3% of the increase (about438K bytes) according to the method in which the recording time isrecorded for each still picture.

[0067] The thumbnail group management information (THMGI) 34 shown inFIG. 7 is thought of as information managing the recording time (RECTM)39 of each still picture (VOB) 1, meaning that it includes the functionsof the still picture recording time management information (RECTMI) 22shown in FIG. 4. Therefore, the pointer information (THMGI_P) 33 shownin FIG. 7 also includes the function of pointer information (RECTMI_P)21 shown in FIG. 4.

[0068]FIG. 8 is a diagram showing the configuration of an embodiment ofthe recording/playback apparatus according to the present invention.

[0069] The recording/playback apparatus may be a special hardware unitor a general-purpose hardware unit such as a personal computercontrolled by a control procedure (hereinafter called a program) whichwill be described later. In either case, a system controller 41 performsoperation according to the program stored in memory 101. The memory 101where the program is stored may be the same storage medium as is used asmemory 102 where the management information is recorded. Or, they may beseparately configured. For example, a storage medium forrarely-rewritten data, such as a read-only memory (ROM) or flash memory,is used for the memory 101, while a storage medium forfrequently-rewritten data, such as a Dynamic Random Access Memory (DRAM)or a Static Random Access Memory (SRAM), is used for the memory 102. Thecontents of the memory 101 where the program is stored may be preset bythe manufacturer before shipping or, as shown in FIG. 11, the programmay be read from another storage medium (computer-readable storagemedium) before the apparatus starts operation.

[0070]FIG. 20 shows an example of the recording/playback apparatusconfigured according to the present invention. Referring to the figure,the recording/playback apparatus comprises a computer system unit101003, a monitor 101001 on which pictures are displayed, speakers101002 from which sounds are output, a mouse 101004 and a keyboard101005 which receive user's instructions, and a disk drive 101006 whichrecords data to, or plays back data from, a storage medium 101007. Thestorage medium 101007 stores thereon the program controlling thecomputer system unit 101003, and the program is read (installed) intomemory 10101 of the computer via the drive 101006 before the computer isused as a recording/playback apparatus. The storage medium 101007 is aread-only disc, such as a CD-ROM or DVD-ROM, or a floppy disk. Inaddition, a rewritable medium such as a DVD-RAM may be used as thestorage medium 101007 to allow the program and the picture/audio data tobe mixed on the same medium.

[0071] First, the recording/playback apparatus shown in FIG. 8 receivesan operation instruction from the user through the user interface 42.The system controller 41 starts operation control of the parts whichwill be described later. At recording time, an input unit 43 receivesthe picture signals and audio signals, and an encoder 44 codes thesignals using the MPEG system. Coded data such as video, still picture,and audio data is entered into a drive 46 via a track buffer 45 forrecording onto a storage medium 47. At this time, the managementinformation generated by the system controller according to the methodshown in FIGS. 1, 4, 6, and 7 is also recorded.

[0072] While coded data is recorded in real time, it is difficult torecord management information at the same time. Therefore, recording ofthe management information is controlled so that it is once recorded inthe memory 102 and then written onto the storage medium 47 after thecoded data is recorded. Reducing the size of the memory 102 is one ofthe objects of the present invention.

[0073] On the other hand, at playback time, the drive reads themanagement information from the storage medium 47 into memory 102. Basedon the management information that was read, the drive reads coded datainto the track buffer 45. A decoder 48 decodes the coded data sent fromthe track buffer 45, and an output unit 49 outputs the decoded data.

[0074] The following describes a computer-readable storage medium forexecuting the still picture recording method and the still pictureplayback method according to the present invention, with emphasis on theoperation of the system controller 41.

[0075]FIG. 9 shows an example of the still picture recording methodaccording to the present invention. Recording starts in step 50. First,in step 51, coded stream data of the still picture (VOB) 1 shown in FIG.1 is recorded on the storage medium as the VOB file 11. Control goes tostep 52.

[0076] In step 52, a check is made to see if the still picture groupmanagement information (VOBGI) 3 corresponding to the still picturegroup (VOBG) 2 including the still picture (VOB) 1 already exists. If itexists, control goes to step 53; if not, control goes to step 58.

[0077] In step 53, the number-of-still-pictures information in the stillpicture group management information (VOBGI) 3 is increased by 1 and theaddress 9 and attribute 10 of the still picture (VOB) 1 recorded in step51 is added to the VOB map 6. Control goes to step 54.

[0078] In step 54, the recording time (RECTM) of the still picturerecorded in step 51 is compared with the first recording time (F_RECTM)7 of the still picture group. If RECTM is earlier than F_RECTM(RECTM<F_RECTM), control goes to step 55; if not, control goes to step56. In normal operation, although RECTM is never earlier than F_RECTM,this comparison is required because the condition (RECTM<F_RECTM) mayoccur, for example, when two or more recording apparatuses share thesame storage medium and there is a difference among the clocks built inthe apparatuses.

[0079] In step 55, the value of F_RECTM is replaced with the value ofRECTM. That is, the value of F_RECTM is set to the earliest time in thestill picture group. Then, control goes to step 56.

[0080] In step 56, the recording time (RECTM) of the still picturerecorded in step 51 is compared with the last recording time (L_RECTM) 8of the still picture group. If RECTM is later than L_RECTM(RECTM>L_RECTM), control goes to step 57; if not, control goes to step61. In normal operation, although RECTM should be later than L_RECTM,this comparison is required because the condition (RECTM <L_RECTM) mayoccur, for example, when two or more recording apparatuses share thesame storage medium and there is a difference among the clocks built inthe apparatuses.

[0081] In step 57, the value of L_RECTM is replaced with the value ofRECTM. That is, the value of L_RECTM is set to the latest time of thestill picture group. Then, control goes to step 61.

[0082] In step 58, new still picture group management information(VOBGI) 3 is generated. The number-of-VOBs information 5 is set to 1,and the address 9 and the attribute 10 are set in the VOB map 6. Then,control goes to step 59.

[0083] In step 59, the recording time (RECTM) of the still picturerecorded in step 51 is set in the first recording time (F_RECTM) 7 ofthe still picture group. Control goes to step 60.

[0084] In step 60, the recording time (RECTM) of the still picturerecorded in step 51 is set in the last recording time (L_RECTM) 8 of thestill picture group. Control goes to step 61.

[0085] In step 61, the still picture group management information(VOBGI) 3 generated or updated described above is recorded on thestorage medium as the VOB management file 12. The recording operationends in step 62.

[0086]FIG. 10 shows an example of the still picture playback methodaccording to the present invention. The figure shows how only the stillpicture (VOB) 1 whose recording time (RECTM) is near a desired timeentered from a user interface 42 is selectively played back.

[0087] Playback starts in step 63. In step 64, a desired time (TM) isentered and control goes to step 65.

[0088] In step 65, the first still picture group management information(VOBGI) 3 is selected for processing. In this case, the first stillpicture group management information (VOBGI) is, for example, the stillpicture group management information (VOBGI) stored first in, andlocated at the beginning of, the VOB management file 12. Then, controlgoes to step 66.

[0089] In step 66, the time (TM) entered in step 64 is compared with thefirst recording time (F_RECTM) 7 and with the last recording time(L_RECTM) 8 in the still picture group management information (VOBGI) 3selected for processing. If TM is equal to or later than F_RECTM andequal to or earlier than L_RECTM, that is, (F_RECTM≦TM≦L_RECTM) issatisfied, control goes to step 67; otherwise, control goes to step 68.

[0090] In step 67, the still picture (VOB) 1 belonging to the stillpicture group (VOBG) 2 managed by the still picture group managementinformation (VOBGI) 3 selected for processing is played back. Controlgoes to step 68.

[0091] In step 68, a check is made to see if the next still picturegroup management information (VOBGI) exists. If it exists, control goesto step 69; if not, control goes to step 70. In this case, the nextstill picture group management information (VOBGI) is, for example, thestill picture group management information (VOBGI) stored following thestill picture group management information (VOBGI) currently selectedfor processing.

[0092] In step 69, the next still picture group management information(VOBGI) is set to the still picture group management information to beprocessed next. Control goes to step 66.

[0093] In step 70, the playback operation ends.

[0094] Through the above operation, only the still pictures (VOB) 1belonging to the still picture groups (VOBG) satisfying the relation(F_RECTM≦TM≦L_RECTM) may be selectively played back.

[0095] Although only DVD-RAM discs are used as examples in the aboveembodiments, it is apparent that the present invention is not limitedthereto but may be used for other recording media.

[0096] The above method achieves the first object of the presentinvention. That is, without increasing the data size of managementinformation, the user can search a huge number of still picturesrecorded on a large-capacity optical disc medium for a desired stillpicture using its recording time (RECTM).

[0097] An embodiment of the present invention that achieves the secondobject will be described with reference to the attached drawings.

[0098] Referring to FIG. 11 which shows the configuration of theembodiment of the present invention, the following describes how therecording sequence and the attributes of still pictures are recorded inthe management information. In the figure, N (an integer equal to orlarger than 1) still pictures (VOB) 101 coded, for example, in the Ipicture compression method of MPEG are grouped into one still picturegroup (VOBG) 102. Group generation is controlled so that the next stillpicture group (VOBG) 102 is generated when the number of still pictures(VOB) 101 of the still picture group (VOBG) 102 reaches a predeterminedvalue (for example, 64) during still picture recording or when theoperation mode is switched from video recording mode to still picturerecording mode. Data (coded stream data) of the still pictures (VOB) 101is recorded on a storage medium as a VOB file 1013 which will bedescribed later, while information used to define the still picturegroups (VOBG) 102 is recorded on the storage medium as a VOB managementfile 1014.

[0099] The VOB management file 1014 comprises management information(VOBGI) 103 corresponding to each still picture group (VOBG) 102. Thatis, each still picture group (VOBG) 102 has its own managementinformation (VOBGI) 103 in this file. Note that information used tomanage M (an integer equal to or larger than 1) pieces of managementinformation (VOBGI) 103 may be provided separately in the VOB managementfile 1014. This information is not shown in the figure because it is notrelated directly to the present invention. The management information(VOBGI) 103 comprises still picture group identification information(VOBG_ID) 104, still picture group address information (VOBG_Address)105, number-of-still-pictures information (VOBI_Number) 106, and a stillpicture management information table (VOBI_Table) 107. Each entry willbe described below.

[0100] The still picture group identification information (VOBG_ID) 104,a unique value in the VOB management file 1014, identifies each piece ofmanagement information (VOBGI) 103 and the corresponding still picturegroup (VOBG) 102. Serial numbers beginning with the start of the VOBmanagement file 1014 may be used for this information, in which case thestill picture group identification information (VOBG_ID) 104 may beomitted.

[0101] The still picture group address information (VOBG_Address) 105indicates the start address of coded stream data of the still picturegroup (VOBG) 102 within the VOB file. The information may also containthe end address.

[0102] The number-of-still-pictures information (VOBI_Number) 106indicates the number of still pictures (VOB) 101 of the still picturegroup (VOBG) 102.

[0103] The still picture management information table (VOBI_Table) 107is composed of still picture management information (VOBI) 108 entriesof the still pictures (VOB) 101 of the still picture group (VOBG) 102.The still picture management information (VOBI) 108 entries are storedin the still picture management information table (VOBI_Table) 107 inthe sequence in which the still pictures (VOB) 101 are stored. Forexample, still picture management information (VOBI) 108-1 shown in FIG.11 corresponds to the still picture (VOB) 101-1.

[0104] The still picture management information (VOBI) 108 is classifiedinto one of the following according to the attribute of thecorresponding still picture (VOB) 101: management information on a stillpicture with no audio (hereinafter called audio) to be played back insynchronization with the still picture (first still picture managementinformation (V_I)) 109, management information on a still picture withonly audio (hereinafter called original audio) recorded almost at thesame time the still picture is recorded (second still picture managementinformation (V_OA_I)) 1010, management information on a still picturewith only added (post-recorded) audio (hereinafter post-recordedaudio)(third still picture management information (V_AA_I)) 1011, andmanagement information on a still picture with both original audio andpost-recorded audio (fourth still picture management information(V_OA_AA_I)) 1012.

[0105] The still picture management information table (VOBI_Table) 107,with this configuration, may hold the recording sequence and theattributes of the still pictures (VOB) 101 in the still picture groupmanagement information (VOBGI) 103. When the still picture (VOB) 101 isdeleted, the corresponding still picture management information (VOBI)108 is also deleted at the same time.

[0106] Next, referring to FIG. 14, the detailed configuration of thestill picture management information (VOBI) 108 will be described. Howto reduce the data size of management information will also bedescribed.

[0107]FIG. 14, (a) shows the configuration of management information ona still picture with no audio (first still picture managementinformation (V_I)) 109. V_I 109 is composed of identificationinformation (V_I_ID) 1033, which is still picture identificationinformation (VOBI_ID) identifying the first still picture managementinformation, and an picture data size (V_Size) 1034. This dataconfiguration, necessary and sufficient for playing back a still picturewith no audio, eliminates redundant parts to minimize the managementinformation data size. How to get the address of the video part (V_Part)will be described later.

[0108]FIG. 14, (b) shows the configuration of management information ona still picture with only original audio (second still picturemanagement information (V_OA_I)) 1010. V_OA_I 1010 is composed ofidentification information (V_OA_I_ID) 1035, which is still pictureidentification information (VOBI_ID) identifying the second stillpicture management information, an picture data size (V_Size) 1036, anoriginal audio data size (OA_Size) 1037, and an original audio playbacktime (OA_PTM) 1038. This data configuration, necessary and sufficientfor playing back a still picture with only original audio, eliminatesredundant parts to minimize the management information data size. How toget the addresses of the video part (V_Part) and the original audio part(OA_Part) will be described later.

[0109]FIG. 14, (c) shows the configuration of management information ona still picture with only post-recorded audio (third still picturemanagement information (V_AA_I)) 1011. V_AA_I 1011 is composed ofidentification information (V_AA_I_ID) 1039, which is still pictureidentification information (VOBI_ID) identifying the third still picturemanagement information, an picture data size (V_Size) 1040, and apost-recorded audio pointer information (AA_I_PTR) 1041 which will bedescribed later. This data configuration, necessary and sufficient forplaying back a still picture with only post-recorded audio, eliminatesredundant parts to minimize the management information data size. How toget the addresses of the video part (V_Part) and the post-recorded audiopart (AA_Part) will be described later.

[0110]FIG. 14, (d) shows the configuration of management information ona still picture with both original audio and post-recorded audio (fourthstill picture management information (V OA_AA_I)) 1012. V_OA_AA_I 1012is composed of identification information (V_OA_AA_I_ID) 1042, which isstill picture identification information (VOBI_ID) identifying thefourth still picture management information, an picture data size(V_Size) 1043, an original audio data size (OA_Size) 1044, an originalaudio playback time (OA_PTM) 1045, and post-recorded audio pointerinformation (AA_I_PTR) 1046 which will be described later. This dataconfiguration, necessary and sufficient for playing back a still picturewith both original audio and post-recorded audio, eliminates redundantparts to minimize the management information data size. How to get theaddresses of the video part (V_Part), the original audio part (OA_Part),and the post-recorded audio part (AA_Part) will be described later. FIG.14, (e) shows the detailed configuration of the still pictureidentification information (VOBI_ID) 1047 described above. The stillpicture identification information (VOBI_ID) 1047 is composed of TY(Type) identifying one of V_I_ID 1033, V_OA_I_ID 1035, V_AA_I_ID 1039,and V_OA_AA_I_ID 1042 and PP (Playback Permission) indicating whether ornot the still picture (VOB) 101 corresponding to the still pictureidentification information (VOBI_ID) 1047 is to be played back. The PPis a flag wherein “0” indicates that the still picture will be playedback normally and “1” indicates that the still picture cannot be playedback. The function of this flag is the same as that described inEuropean Patent Application No. 99304691.1 or the corresponding U.S.patent application Ser. No. 09/332,882 described above.

[0111] Classifying the still picture attributes into four types as shownin (a) to (d) of FIG. 14 and then, for each of them, providing stillpicture management information (VOBI) 108 of the necessary andsufficient data size minimize the data size of the VOB management file1014. For example, when four types of still pictures, that is, (a) stillpicture with no audio, (b) still picture with only original audio, (c)still picture with only post-recorded audio, and (d) still picture withboth original audio and post-recorded audio, are recorded, the totaldata size of the picture management information (V_I) 1017 and the audiomanagement information (A_I) 1020 is 2 bytes for (a), 11 bytes for (b),11 bytes for (c), and 20 bytes for (d), respectively. In contrast, whenthe method shown in FIG. 14 is used, the data size of the still picturemanagement information (VOBI) 108 is 2 bytes for (a), 6 bytes for (b), 4bytes for (c), and 8 bytes for (d). For (c) and (d), the managementinformation on the post-recorded audio part (AA_Part) is requiredseparately. This will be described later.

[0112] In addition, the still picture identification information(VOBI_ID) 1047 placed at the start of each of still picture managementinformation (VOBI) 108 entries gives us information on the data size ofthe still picture management information (VOBI) 108. For example, the TYvalue of “00”, if stored in the still picture identification information(VOBI_ID) 1047, indicates that the VOBI_ID(1047) is V_I 109 and that thetotal data size is 2 bytes. Therefore, the recording position of VOBI#3(108-3) in the still picture management information table (VOBI_Table)107 shown in FIG. 11 may be calculated by finding the recording positionof VOBI #2(108-2) from the data size in VOBI #1(108-1) and then findingthe recording position of VOBI #3(108-3) from the data size of VOBI#2(108-2).

[0113]FIG. 15, (a) shows an example of file structure used in theembodiment of the present invention. On recording media such as aDVD-RAM, coded stream data such as still pictures, managementinformation, and so on are recorded as logical files. A storage medium,with a directory structure beginning at the root directory 1048, usuallyhas the above-described VOB file 1013 and VOB management file 1014generated and stored in a subdirectory 1049. Note that, instead of usingthe subdirectory 1049, the VOB file 1013 and the VOB management file1014 may be recorded directly below the root directory 1048. The VOBfile 1013 and the VOB management file 1014 may also be stored in anothersub-directory which is below the sub-directory 1049.

[0114] Referring to FIG. 15, (b) in which an example of the VOB file1013 is shown, how to get addresses from the data size information shownin FIG. 14 will be described. Within one still picture group (VOBG) 102,only the picture part (V_Part) and the original audio part (OA_Part) ofthe still picture (VOB) 101 are recorded continuously in the VOB file1013 as shown in the figure. In other words, when other types of datasuch as video data must be recorded in the VOB file 1013, another stillpicture group (VOBG) 102 will be generated as described above. Thefigure shows an example of the contents of a VOB file. It contains thepicture part (V_Part #1) 1050 of still picture #1(VOB #1), the picturepart (V-Part #2) 1051 of still picture #2(VOB #2) and its original audiopart (OA_Part #2) 1052 recorded almost at the same time, the picturepart (V_Part #3) 1053 of still picture #3(VOB #3), the picture part(V_Part #4) 1054 of still picture #4(VOB #4) and its original audio part(OA_Part #4) 1055 recorded almost at the same time. In this case, forexample, the start address of the picture part (V_Part #3) 1053 of stillpicture #3(VOB #3) is calculated by adding up the data size (V_Size #1)of V_Part #1(1050), the data size (V_Size #2) of V_Part #2(1051), andthe data size (OA_Size #2) of OA_Part #2(1052) and then adding to theresult the start address of V_Part #1(1050) recorded in the stillpicture group address information (VOBG_Address) 105. Adding up datasizes to get an address like this eliminates the need to update thecontents of the management information of the following still picture#4(VOB #4) even when the still picture #3(VOB #3) is deleted. Therefore,this configuration significantly reduces the time needed to reconfigurethe management information.

[0115] Since post-recorded audio parts (AA_Part) are added independentlyof the sequence in which the picture parts (V_Part) are recorded andbecause, in comparison with picture parts (V_Part) and original audioparts (OA_Part), there are far fewer post-recorded audio parts, thepost-recorded audio parts (AA_Part) are configured separately fromV_Part and OA_Part. For example, the audio management information (A_I)1020 is provided in the audio management information table (A_I_Table)1019 shown in FIG. 12 and, in that table, the address information(A_Address) 1023, audio data size (A_Size) 1024, and audio playback time(A_PTM) 1025 of the post-recorded audio part (AA_Part) are recorded.Storing a pointer to the number (such as #1) of the audio managementinformation (A_I) 1020 in the post-recorded audio pointer information(AA_I_PTR) 1041, 1046 shown in FIG. 14 allows the address, data size,and playback time of the post-recorded audio part (AA_Part)corresponding to the still picture management information (VOBI) to beobtained. Also, because the number of post-recorded audio entries islimited to one, there is no need to provide the audio pointerinformation (A_I_PTR) 1026 to link to other audio data. This means thatthe audio pointer information (A_I_PTR) 1026 may be omitted.

[0116] In addition, the data configuration composed only ofpost-recorded audio parts (AA_Part) allows an address to be calculatedby adding up the audio data sizes (A_Size) 1024 beginning at the start.This means that the audio data address information (A_Address)(1023) maybe omitted.

[0117]FIG. 16 is a diagram showing the configuration of an embodiment ofthe recording/playback apparatus according to the present invention. Therecording/playback apparatus may be a special hardware unit or ageneral-purpose hardware unit such as a personal computer controlled bya control procedure (hereinafter called a program) which will bedescribed later. In either case, a system controller 1056 performsoperation according to the program stored in memory 10101. The memory10101 where the program is stored may be the same storage medium as isused as memory 10102 where the management information is recorded. Or,they may be separately configured. For example, a storage medium forrarely-rewritten data, such as a read-only memory (ROM) or flash memory,is used for the memory 10101, while a storage medium forfrequently-rewritten data, such as a Dynamic Random Access Memory (DRAM)or a Static Random Access Memory (SRAM), is used for the memory 10102.The contents of the memory 10101 where the program is stored may bepreset by the manufacturer before shipping or, as shown in FIG. 20, theprogram may be read from another storage medium (computer-readablestorage medium) before the apparatus starts operation.

[0118]FIG. 20 shows an example of the recording/playback apparatusconfigured according to the present invention. Referring to the figure,the recording/playback apparatus comprises a computer system unit101003, a monitor 101001 on which pictures are displayed, speakers101002 from which sounds are output, a mouse 101004 and a keyboard101005 which receive user's instructions, and a disk drive 101006 whichrecords data to, or plays back data from, a storage medium 101007. Thestorage medium 101007 stores thereon the program controlling thecomputer system unit 101003, and the program is read (installed) intomemory 10101 of the computer via the drive 101006 before <the computeris used as a recording/playback apparatus. The storage medium 101007 isa read-only disc, such as a CD-ROM or DVD-ROM, or a floppy disk. Inaddition, a rewritable medium such as a DVD-RAM may be used as thestorage medium 101007 to allow the program and the picture/audio data tobe mixed on the same medium.

[0119]FIG. 16 is a diagram showing the configuration of an embodiment ofthe recording/playback apparatus according to the present invention.When a user interface 1057 of the recording/playback apparatus receivesan operation instruction from the user, a system controller 1056 startsoperation control of the parts which will be described later. Atrecording time, an input unit 1058 receives the picture signals andaudio signals, and an encoder 1059 codes the signals using the MPEGsystem. Coded data such as video, still picture, and audio data isentered into a drive 1061 via a track buffer 1060 for recording onto astorage medium 1062. At this time, the management information generatedby the system controller 1056 according to the method shown in FIGS. 11and 14 is also recorded. While coded data is recorded in real time, itis difficult to record management information at the same time.Therefore, recording of the management information is controlled so thatit is once recorded in the memory 10102 and then written onto thestorage medium 1062 after the coded data is recorded. Reducing the sizeof the memory 10102 is one of the objects of the present invention.

[0120] On the other hand, at playback time, the drive 1061 reads themanagement information from the storage medium 1062 into memory 10102and, then, based on the management information that was read, readscoded data into the track buffer 1060. A decoder 1063 decodes the codeddata sent from the track buffer 1060, and an output unit 1064 outputsthe decoded data. Because the detailed operation of the above units isdisclosed, for example, in European Patent Application No. 99304691.1 orcorresponding U.S. patent application Ser. No. 09/332,882 and itsdetailed configuration is known, they are not shown here. The followingdescribes the recording method and the playback method according to thepresent invention, with emphasis on the operation of the systemcontroller 1056 (that is, the contents of the program).

[0121]FIG. 17 shows an example of the original recording methodaccording to the present invention. Recording starts in step 1065. Instep 1066, the still picture group (VOBG) 102 to which a still picture(VOB) 101 is to belong and the corresponding still picture groupmanagement information (VOBGI) 103 are determined. Then, control goes tostep 1067. At this time, if another still picture (VOB) 101 was recordedimmediately before, the still picture group (VOBG) 102 and the stillpicture group management information (VOBGI) 103 used in recordingimmediately preceding still picture (VOB) 101 may be used. If the numberof still pictures in the still picture group (VOBG) 102 has reached apredetermined number (for example, 64) or if other types of data such asvideo data was recorded immediately before, a new still picture group(VOBG) 102 and still picture group management information (VOBGI) 103may be generated.

[0122] In step 1067, the coded stream data of the picture part (V_Part)of the still picture (VOB) 101 is recorded on the storage medium 1062 asthe VOB file 1013. Control goes to step 1068.

[0123] In step 1068, a check is made to see if the original audio is tobe recorded. If it is not to be recorded, control goes to step 1069; ifit is to be recorded, control goes to step 1070. For this checking, theuser may decide, before the still picture is recorded, the operationmode indicating whether the original audio is to be recorded. With thisuser-decided state stored in the mode switch or in the mode memoryprovided in the recording apparatus, whether or not the original audiois to be recorded may be determined according to the stored state.

[0124] In step 1069, the management information on a still picture withno audio (first still picture management information (V_I)) 109 is addedto the end of the still picture management information table(VOBI_Table) 107 within the still picture group management information(VOBGI) 103 shown in FIG. 11. Then, the identification information(V_I_ID) identifying that the information is the first still pictureinformation and picture data size (V_Size) 1034 are recorded in the(first still picture management information (V_I)) 109 as shown in FIG.14. Control then goes to step 1072.

[0125] In step 1070, the coded stream data of the original audio part(OA_Part) to be played back in synchronization with the still picture(VOB) 101 is added to the VOB file 1013, and control is passed to step1071.

[0126] In step 1071, the management information on a still picture withonly original audio (second still picture management information(V_OA_I)) 1010 is added to the end of the still picture managementinformation table (VOBI_Table) 107 within the still picture groupmanagement information (VOBGI) 103. Then, the identification information(V_OA_I_ID) identifying that the management information is the secondstill picture management information, the picture data size (V_Size)1036, the original audio data size (OA_Size) 1037, and the originalaudio playback time (OA_PTM) 1038 are recorded in the (V_OA_I) 1010 asshown in FIG. 14. Control then goes to step 1072.

[0127] In step 1072, the original recording operation ends.

[0128]FIG. 18 shows an example of the post-recording method used in thepresent invention. Recording starts in step 1073. In step 1074, the userselects the still picture (VOB) 101 for which audio is to bepost-recorded. At the same time, the system controller (1056) of therecording unit determines the still picture group (VOBG) 102 to whichthe still picture (VOB) 101 belongs as well as the corresponding stillpicture group management information (VOBGI) 103 and still picturemanagement information (VOBI) 108. Then, control goes to step 1075.

[0129] In step 1075, a check is made for the still picture managementinformation (VOBI) 108 selected in step 1074 to determine the type(V_I(109), V_OA_I(1010), V_AA_I(1011), or V_OA_AA_I(1012)) by referringto the VOBI_ID(1047) shown in FIG. 14. Then, control is passed to step1076 if the type is V_I(109), to step 1077 if the type is V_OA_I(1010),or to step 1078 if the type is V_AA_I(1011) or V_OA_AA_I(1012).

[0130] In step 1076, V_I(109) is changed to V_AA_I(1011) and control ispassed to step 1079. That is, as shown in FIG. 14, the value of TY in(VOBI_ID) 1047 is changed from “00” to “10” and, at the same time, themanagement information following the VOBI_ID(1047) is shifted two bytesin memory to vacate a two-byte area for storing the post-recorded audiopointer information (AA_I_PTR) 1041.

[0131] In step 1077, V_OA_I(1010) is changed to V_OA_AA_I(1012) andcontrol is passed to step 1079. That is, the value of TY in (VOBI_ID)1047 is changed from “01” to “11” and, at the same time, the managementinformation following the VOBI_ID(1047) is shifted two bytes in memoryto vacate a two-byte area for storing the post-recorded audio pointerinformation (AA_I_PTR) 1046.

[0132] In step 1078, the post-recorded audio part (AA_Part)corresponding to this still picture is located using AA_I_PTR(1041)recorded in V_AA_I(1011) or using AA_I_PTR(1046) recorded inV_OA_AA_I(1012) and is deleted. Control goes to step 1079.

[0133] In step 1079, the coded stream data of the post-recorded audiopart (AA_Part) is recorded on the storage medium 1062. Control goes tostep 1080.

[0134] In step 1080, the post-recorded audio pointer informationAA_I_PTR(1041 or 1046) providing a link to the post-recorded audio part(AA_Part) recorded in step 1079 is set in the VOBI_ID(1047). In step1081, post-recording of audio data ends.

[0135]FIG. 19 shows an example of playing back still pictures accordingto the present invention. Playing back starts in step 1082. In step1083, the still picture group (VOBG) 102 to be played back and thecorresponding still picture group management information (VOBGI) 103 aredetermined. Then, control goes to step 1084. At this time, the user maydirectly select the still picture group (VOBG) 102 to be played back.Or, the still picture group management information (VOBGI) 103 may beselected sequentially according to the sequence in which still picturegroups (VOBG) 102 were actually recorded, according to the sequence inwhich the still picture group management information (VOBGI) 103 isrecorded in the VOB management file 1014, or according to auser-specified predetermined playback sequence. Note that theuser-specified playback sequence is recorded in CellI in PGCI in thePGCI table described in European Patent Application No. 99304691.1 orcorresponding U.S. patent application Ser. No. 09/332,882.

[0136] In step 1084, the still picture (VOB) 101 is played backaccording to the sequence in which the still picture managementinformation (VOBI) 108 entries are recorded in the still picturemanagement information table (VOBI_Table) 107 in the still picture groupmanagement information (VOBGI) 103. The procedure is shown in steps 1085to 1092.

[0137] In step 1085, the still picture management information (VOBI) 108corresponding to the still picture (VOB) 101 to be displayed first isselected for processing, and control is passed to step 1086. At thistime, the first VOBI 108 in VOBI_Table 107 (VOBT #1(108-1) in FIG. 11)or a user specified VOBI_108 may be processed. Note that theuser-specified VOBI 108 may be recorded in Cell_Start_Video in CellIdescribed in European Patent Application No. 99304691.1 or correspondingU.S. patent application Ser. No. 09/332,882.

[0138] In step 1086, the V-Sizes 1034, 1036, 1040, or 1043 and OA_Sizes1037 or 1044 recorded in the VOBI 108 entries from the first (VOBI) 108in the VOBI_Table 107 to the VOBI 108 immediately preceding the VOBI 108to be processed are added up. The resulting value is added to the startaddress stored in the still picture group address information(VOBG_Address) 105 to find the address of the desired picture part(V_Part). Next, the data size of the V_Part is obtained from the V_Size1034, 1036, 1040, or 1043 recorded in the VOBI 108 determined in step1085, and the V_Part is read from the storage medium 1062. The decoder1063 decodes the picture data, and the output unit 1064 plays back thepicture. Control goes to step 1087.

[0139] In step 1087, a check is made for the VOBI 108 to be processed todetermine the type (V_I(109), V_OA_I(1010), V_AA_I(1011), orV_OA_AA_I(1012)) by referring to the (VOBI_ID) 1047. Then, control ispassed to step 1091 if the type is V_I 109, to step 1088 if the type isV_OA_I(1010), to step 1089 if the type is V_AA_I(1011), or to step 1090if the type is V_OA_AA_I(1012).

[0140] In step 1088, the data size of the original audio part (OA_Part)is obtained from the OA_Size 1037 recorded in the V_OA_I(1010) and, atthe same time, the data size of the V_Part is added to the address ofthe V_Part obtained in step 1086 to find the address of the OA_Part. TheOA_Part is read from the storage medium 1062. The decoder 1063 decodesthe audio data, and the output unit 1064 plays back the audio. Controlgoes to step 1091.

[0141] In step 1089, the post-recorded audio part (AA_Part)corresponding to the still picture is located using the AA_I_PTR 1041recorded in the V_AA_I 1011. The post-recorded audio part (AA_Part) isread from the storage medium 1062. The decoder 1063 decodes the audiodata, and the output unit 1064 plays back the audio. Control goes tostep 1091.

[0142] In step 1090, which audio part, either original audio part(OA_Part) or post-recorded audio part (AA_Part), is to be played back isdetermined according to the user's selection. When the OA_Part is to beplayed back, the OA_Part is read for playback using the OA_Size 1044recorded in the V_OA_AA_I 1012 according to the procedure used in step1088. When the AA_Part is to be played back, the AA_Part is read forplayback using the AA_I_PTR 1046 recorded in the V_OA_AA_I(1012)according to the procedure used in step 1089. Control goes to step 1091.

[0143] In step 1091, a check is made to see if the VOBI 108 beingprocessed is the last VOBI. If so, control goes to step 1093; if not,control goes to step 1092. At this time, the last VOBI may be the lastVOBI 108 (VOBI #5(1085) in FIG. 11) recorded in the VOBI_Table 107 or auser-specified VOBI 108. Note that a user specified VOBI 108 may berecorded in Cell_End_Video in Cell described in European PatentApplication No. 99304691.1 or corresponding U.S. patent application Ser.No. 09/332,882.

[0144] In step 1092, the next VOBI 108 in the VOBI_Table 107 is selectedfor processing and control goes back to step 1086.

[0145] In step 1093, the playback operation ends.

[0146] The above operation enables still pictures (VOB) 101 to be playedback according to the sequence in which the still picture managementinformation (VOBI) 108 entries are recorded in the still picturemanagement information table (VOBI_Table) 107.

[0147] Although only DVD-RAM and DVD-R discs are used as examples in theabove embodiment, it is apparent that the present invention is notlimited thereto but may be used for other recording media. While thedata sizes of the parts (101 byte and so on) are shown in FIG. 14, theyare for illustrative purposes only and the present invention is notlimited to these sizes.

[0148] The method described above achieves the second object of thepresent invention. That is, the method records a huge number of stillpicture data pieces and audio data to be played back in synchronizationwith the still picture data onto a large-capacity optical disc medium.Even when some still pictures are deleted, the method significantlyreduces the time needed to reconfigure management information and thedata size of the management information.

What is claimed is:
 1. A playback apparatus for playing back pictureinformation from a storage medium storing still picture group managementinformation (VOBGI) for managing still picture data (VOB) and N stillpicture data (VOB) as a still picture group (VOBG), where N is aninteger number equal to or larger than one, wherein said still picturegroup management information (VOBGI) includes a first recording time(F_RECTM) at which the still picture data (VOB) in said still picturegroup (VOBG) was recorded first and a last recording time (L_RECTM) atwhich the still picture data (VOB) in said still picture group (VOBG)was recorded last, said apparatus comprising: a user interface forinputting a predetermined time (TM); a control unit for comparing saidpredetermined time with said first and last recording times (F_RECTM,L_RECTM); and means for reading out the still picture data (VOB) fromsaid storage medium and playing back said still picture by selectivelyplaying back the still picture data (VOB) belonging to said stillpicture group (VOBG) satisfying a condition (F_RECTM<TM<L_RECTM) inwhich said predetermined time (TM) is equal to or later than said firstrecording time (F_RECTM) and equal to or earlier than said lastrecording time (L_RECTM).